Design and Materials Applications of Quadruply Hydrogen Bonding Modules

Part I Despite the remarkable advances made in recent years toward the development of hydrogen bonding modules, there still exists a recognized need to expand the ???supramolecular toolkit??? with synthetically accessible, high-affinity, high-fidelity modules that are readily incorporated into materials. Part I of this dissertation describes the design and synthesis of a high-affinity, high-fidelity quadruply hydrogen bonding heterocomplex. A novel urea of 7-deazaguanine (DeUG) was designed as a synthetically versatile and chemically robust analogue of Park and Zimmerman???s urea of guanosine (UG), and as complement to 2,7-diamido-1,8-naphthyridine (DAN). Analytically pure DeUG, which can be easily incorporated into materials, can be readily prepared on multigram scale in six steps and an overall yield of ca. 35% without the need to resort to column chromatography for purification at any stage. 1H NMR dilution studies and van???t Hoff analysis revealed that DeUG only moderately self-associates (Kdimer = 610 M^-1). Moreover, because DeUG is preorganized into the complementary hydrogen bonding motif to DAN, DeUG displays exceptionally high-affinity with DAN (Kassoc = 2 x 10^8 M^-1) in organic solvents. The low propensity of DeUG to dimerize, coupled with the high stability of the DeUG??DAN heterocomplex, results in a heterocomplex with excellent fidelity. Part II Hydrogen bonding homocomplexes and heterocomplexes have enjoyed enormous success toward the creation of novel materials with unprecedented properties. However, many challenges and unique opportunities remain. Part II of this dissertation describes materials applications of the DeUG??DAN heterocomplex. Chapter 3 details the development and application of a photoresponsive DAN (pDAN). Through covalent incorporation of anthracene moieties, which are capable of reversible, photochemical dimerization, into DAN, it is possible to modulate the DeUG??DAN binding event. This, in turn, allowed for the reversible formation of supramolecular network polymers as demonstrated by the reversible transition from gel to solution phases. In Chapter 4, the application of the DeUG??DAN heterocomplex in the arena of surface chemistry is described. Several types of siliceous surfaces and nanoparticles, and polymer beads were covalently modified to bear DeUG. These surfaces were characterized by a number of complementary surface analysis techniques, such as AFM, SIMS and XPS. Self-assembly of DAN and DAN-functionalized polymers on these materials was demonstrated. Additionally, the application of these functionalized surfaces and polymers as interfacial adhesion promoters is described